<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Title</title>
</head>
<style>
    .container{
        display: flex;
        /*flex-direction: row;
        flex-wrap: wrap;*/
        flex-flow: row nowrap;
    }
    .item{
        background-color: #f4f4f4;
        border: 1px solid #444;
        padding: 1rem;
        text-align: center;
        margin: 0.75rem;
        flex: 1;
    }
    .item:first-child{
        flex: 1;
    }

</style>
<body>
<div class="container">
    <div class="item">
        <h3>Item1</h3>
    </div>
    <div class="item">
        <h3>Item2</h3>
    </div>
    <div class="item">
        <h3>Item3</h3>
    </div>
    <div class="item">
        <h3>Item3</h3>
    </div>
    <div class="item">
        <h3>Item3</h3>
    </div>
    <div class="item">
        <h3>Item3</h3>
    </div>
    <div class="item">
        <h3>Item3</h3>
    </div>
    <div class="item">
        <h3>Item3</h3>
    </div>
</div>
</body>
</html>
